In the field of mechanical, electronic, and semiconductor industries, sputtering is one of the most popular methods for forming a paint film (thin film) on the surface of a material to add on a certain character to the material. Sputtering is a method of physical vapor deposition, which is broadly adopted by the industries for its wide applications as well as being unrestricted to the material, either metal or non-metal. The concept of sputtering is that atoms are ejected from the surface of a solid target material due to bombardment of the target by energetic ions in a vacuum environment and then adhered to a substrate (the material) to form a thin film.
The fundamental principle of sputtering is to bombard the surface of the solid target with accelerated ions and end up with sputtered atoms from the surface of the solid target after a momentum exchange between the ions and the atoms. Usually, the target is located at the cathode while the matter to be plated (say specimen substrates or disks) is located at the anode. To stimulate the plasma of a sputtering gas, a voltage of multi-million volts is applied to the cathode. The negative voltage applied to the cathode accelerates positive ions in the sputtering gas plasma toward the surface of the cathode. When the positive ions eventually collide with the surface of the target, atoms on the surface of the target are ejected out and move toward the substrate located at the anode. The atoms will then be plated on the surface of the substrate.
Based on the electrical power used during the process, the sputtering can be categorized into DC sputtering and RF sputtering. DC sputtering is often used for semiconductor materials. The reactive sputtering can be made with different input gases. In general, oxygen or nitrogen is input for making oxide or nitride respectively. RF sputtering could be widely applied to a variety of materials, mostly to non-conducting materials.
The object body for surface treatment is usually of a flat shape. Therefore, during the sputtering process, the object body needs to be fastened only, or merely be rotated at one degree of freedom, to achieve the purpose of homogeneous coating film. However, due to a cylinder shape having not only a 360-degree surface but also a length, simply fastening the object body or rotating it at one degree of freedom may end up with ultra thickness at some particular spots and cannot achieve the effect of homogeneous film coating.
To overcome the issue set forth in the prior paragraph, the present invention employs combinations of mechanical structures to acquire switching as well as combination of power directions and achieve the effect of multi-degree-of-freedom rotation simultaneously.